In this blog post, we will examine the impact of anesthesia on the development of medicine, from the days when medieval barbers performed surgery to the era of modern surgeons.
ER, House M.D., New Amsterdam, The Good Doctor, etc. In American medical dramas, surgeons are portrayed as gods in the operating room. They successfully perform complex surgeries and save patients’ lives, leaving viewers in awe. While this image has contributed to portraying surgeons as heroes, the reality of the medical field requires thorough preparation, close collaboration, and countless trials and errors. It is hard to believe that such impressive and important surgical procedures were once performed by barbers in the Middle Ages. However, in less than 200 years, advancements in sterilization, blood transfusion, hemostasis, infection control, and anesthesia led to remarkable progress in surgery.
What does it mean to be a skilled surgeon? While there are various criteria today, in the past, the most skilled surgeons were those who could perform surgeries as quickly as possible. In fact, there were surgeons who could amputate a leg in just three minutes. Without anesthesia, it was necessary to reduce surgery time to minimize pain, and time was also crucial in preventing complications such as infections. An interesting point here is that these early surgeons had to exert tremendous concentration and physical ability to win the battle against time. The fact that their skills were not limited to physical ability is connected to the subsequent development of anesthetics.
Although anesthetics did not exist in the past, there were methods that produced similar effects. In extreme cases, people were beaten unconscious before surgery, though more advanced methods also existed. Ancient Egyptian and Assyrian physicians would simultaneously compress the two carotid arteries in the neck to reduce the amount of blood flowing to the brain, thereby cutting off oxygen supply and blurring the patient’s consciousness, allowing surgery to proceed. Additionally, the Egyptians discovered that opium, a type of narcotic, alleviated pain, while the Assyrians created their own painkillers by mixing belladonna, cannabis, and mandrake root. In medieval Arabia, inhalation anesthetics were developed.
It was thanks to the knowledge accumulated by numerous ancient civilizations that an understanding of anesthesia began to deepen. However, at the time, there was little understanding of why these methods were effective or exactly how they worked. When did anesthetics in the modern sense first appear? A representative example is nitrous oxide, also known as laughing gas. In the late 18th century, Joseph Priestley first isolated nitrous oxide, and Sir Humphry Davy discovered that this gas had anesthetic effects along with inducing drowsiness. However, at the time, this was considered more of an interesting pastime than a medically significant invention. It was not until an American dentist used laughing gas to painlessly extract a patient’s tooth that the use of anesthetics began to gain traction in various fields.
Following nitrous oxide, various anesthetics such as diethyl ether and chloroform appeared one after another. However, not all anesthetics are safe. While chloroform has the advantage of being less flammable than ether, it has the potential to cause problems. Additionally, since it contains many narcotic substances, improper use can lead to addiction or even death.
Looking back at history, the discovery of anesthetics appears to be highly accidental. This fact that such an important discovery often originates from experimental curiosity is a prime example of how science progresses. So, what is the principle behind anesthesia?
Currently, various types of anesthetics are used to anesthetize different parts of the body, but this article will focus on general anesthesia. When general anesthesia is administered, the primary site of action of the anesthetic is the reticular activating system (RAS) in the brainstem. The brainstem connects the brain to the spinal cord and supports vital functions such as breathing and circulation, making it a region directly related to life. Among these, the reticular activating system serves as a pathway for transmitting sensory information from the external environment to the brain, acting as a filter that determines what the brain should perceive. It also plays a role similar to that of a stimulant, helping to maintain clear consciousness. Anesthetics function by blocking the transmission of information to the reticular activating system. When external stimuli are not transmitted to the brain, it is impossible to maintain an aroused state, so anesthesia causes loss of consciousness and sensation.
To explain in detail how information transmission to the limbic system is blocked, we must first understand how stimuli are transmitted along nerves. Like all other cells, nerve cells have a membrane composed mainly of phospholipids, which are fat-soluble. Additionally, they have a very elongated shape compared to other cells. Within a single nerve cell, electrical stimuli travel along the membrane to transmit signals. Signal transmission between adjacent nerve cells occurs through the release of signaling molecules (chemical substances) at the synapses—the spaces between adjacent nerve cells—which are then absorbed by the next cell. The release of these substances is regulated by ion channels in the cell membrane.
Anesthetics dissolve in the lipid layer of the cell membrane, increasing its fluidity. This alters the structure of the ion channels present in the cell membrane. The inefficient movement of ions through these structurally altered channels results in neurons becoming less responsive to electrical stimuli. This state, where the ability of neurons to transmit stimuli is impaired, is referred to as anesthesia.
Since anesthetics act on cell membranes, they have a close correlation with their lipophilicity. Commonly used anesthetics in clinical practice include nitrous oxide (Nitrous Oxide), halothane (Halothane), ethrane (Ethrane), and forane (Forane), with newer agents such as desflurane (Desflurane) and sevoflurane (Sevoflurane) recently introduced. Interestingly, these anesthetics are selected based on the individual patient’s condition and the characteristics of the surgery, and ongoing research aims to enhance their efficacy and safety.
The future development of anesthesia remains uncertain, and recent cases of misuse of opioid anesthetics like propofol, referred to as “milk injections,” have become more prevalent, so caution is advised. At the same time, future anesthetics are expected to become more sophisticated, with the development of personalized treatment methods tailored to individual patients, leading to further improvements in the safety and efficacy of anesthesia.
